Core drill



Aug. 22, 1933. J. H. HOWARD CORE DRILL Filed May 18 1931 2 Sheets-Sheetl J. H. HOWARD Aug. 22, 1933.

CORE DRILL Filed 'May 18,

lll'.

Patented Aug. 22, 1933 CORE DRILL John ll. Howard, Huntington Park,Calif., as-

signor to Globe Oil Tools Company, Los Nietos, Calif., a Corporation ofCalifornia Application May 18, 1931. Serial No. 538,211

8 Claims.

This invention relates to a well tool, and relates more particularly toa core drill for obtaining a core or sample of the formation in a wellbore. It is a general object of the present invention to provide asimple, practical, and improved core drill for use in connection withthe rotary method of well drilling.

Another object of the inventionis to provide a core drill having noveland effective means l for handling the circulation huid. The toolprovided by the present invention includes an inner cutter and an outercutter and has an annular iluid passage between the two cutters thatdischarges the circulation fluid into the bottom of the well bore in amanner so that it does not cut out or wash out the core being taken.

It is another objectof the invention to provide a well tool of thecharacter mentioned in which the inner cutter or core cutter properprojects downwardly beyond the outer cutter and is formed so as toprotect the. core against disintegration by the circulation fluid.

It is another object of the invention to provide a core drill of thecharacter mentioned in which the inner and outer cutters overlap intheir action on the formation so as to remove all of the formation atthe bottom of the well bore with the exception of the central core whichis re. ceived and retained within the core barrel. The formation andarrangement of cutting parts included in the present inventionpositively prevents the production of ns or projections of formation inthe bottomv of the well bore in the :1,5 event that the edges of thecutting teeth or cutting parts wear away. It is an object of theinvention to provide a core taking tool of the character mentioned inwhich the inner and outer cutters are independ- 43 ently and removablymounted so as to be readily replaceable and/or exchangeable to adapt thetool for use in various formations.

Another object of this invention is to provide a core. drill of thecharacter mentioned in which barrel are vertically slidable as a'unitrelative to the outer barrel and outer cutter. It is a feature of thepresent invention that the inner cutter carried by the corev receivingbarrel may pass bo ahead of the outer cutter when the tool breaksthrough a hard formation into a soft formation so as to prevent loss ofthe core.

Alfurther object of the invention is to provide a novel and effectivemeans for catching or retaining the core and for cutting off the core'.

Other objects and features of the invention the inner cutter, the corecatcher, and the core (Cl. Z-72) will be best and more fully understoodfrom the following detailed description of a typical form andapplication of the invention, throughout which description referencewill be had to the accompanying draWings,`in which:

Fig. 1 is a side elevation of the tool provided by the presentinvention, showing it in operation at the bottom o f a well bore on theend of an operating string of pipe. Fig. 2 is an enlarged verticaldetailed sectional view of one embodiment of the invention, showing itin operation within the well bore. Fig. 3 is a bottom plan view of thetool, be ing a view taken as indicated by line 3-3 on Fig. 2.' Fig. 4 isan enlarged transverse detailed sectional view taken as indicated byline-4 4 on 70 Fig. 2. .Fig. 5 is an enlarged transverse detailedsectional view taken -as indicated by line 5--5 on Fig. 2. Fig. 6 is anenlarged side elevation of the lower end part of the tool. Fig. 7 is avertical detailed sectional view of the embodiment of the inventionillustrated in Figs. 2 to 6 inclusive, being a view taken as indicatedby line 7 7 on Fig. 6 showing the core cutting dogs in the actuated orcore cutting and supporting position. Fig. 8 is a vertical detailedsectional view of the 80 other embodiment of the invention.

The drills or tools provided by this invention are intended to beemployed for obtaining cores or samples of the formation at the ybottomof a well bore, for example, at the Vbottom of an oil well or gas well.The invention -provides two forms or embodiments differentiated fromeach other principally in the form or type of core catcher or coreretaining means. The form of the invention illustrated in Figs. 1 to linclusive `of /90 the drawings includes a core catching and retainingmeans that is operable to cut off the core or sample on the formationobtained in the core barrel and to hold or retain it in the core barrel,while the form of the invention disclosed in Fig.' 8 includes a corecatching means consisting 'of sets or series of spring fingers forgripping and holding the core passed into the core barrel.

The embodiment of the invention disclosed in Figs. 1 to 7 inclusive ofthe drawings includes, generally, an outer barrel 10, a bit head orouter cutter 11 carried at the lower end of the outer barrel 10, a coreretaining barrel or inner barrel 12 within the barrel 10, an innercutter 13 carried at the lower end of the inner barrel or core barrel12, and core catching means 14.

The outer barrel 10 constitutes the body or main portion of the tool andis an elongated tubular member surrounding the core barrel 12 andcarrying the outer cutting means 11. The outer barlower end of a stringof drill pipe P and may be connected with the operating string in anysuitable manner. In the particular case illustrated in the drawings, theupper end of the outer barrel 10 is screw-threaded into the lower end ofa sub l5. The sub may be provided at its upper end with a screw-threadedpin 16 for connecting with a tool joint section or coupling member 17 onthe lower end of the string of drill pipe P. The outer barrel 10 may beof any suitable length, and its lower end may be screw-threaded into atubular connecting member or sub 18.

'I he outer cutter or main cutting means 11 is carried at the lower endof the outer barrel 10 and is provided to make an annular out in theformation. In accordance with the present invention, the main cuttingmeans 11 is removably carried at the lower end of the outer barrel 10.In the present embodiment of the invention, the outer or main cuttingmeans 11 includes a body 19 and a bit vhead 20. The body 19 is in thenature of a tubular connecting member or coupling for mounting the bithead 20 on the lower end of the' sub 18. It is to be understood that thebit head 20 may-be attached directly to the lower end of the outerbarrel 10 if desired. The body 19 may be of substantially the sameinternal and external diameter as the sub 18 and may have ascrew-threaded connection 21 with the lower end of the sub. The cutteror bit head 20 is annular or tubular in its general configuration and isremovably attached to the body 19. The bit head 20 is provided at itsupper end with a socket 22 for receiving a screw-threaded` pin 23 on thelower end of the body 19.

A plurality of outwardly projecting cutting parts or blades 24 isprovided on the bit head 20. There may be any suitable number of cuttingblades 24 and they may be equally or symmetrically spaced around the bithead. In the case illustrated in the drawings, there are four equallyspaced cutting blades 24 projecting outwardly from the bit head 20. Theblades 24 are inclined or pitched downwardly and forwardly, relative tothe direction of rotation of the tool when in operation, and areprovided with outer cutting edges 25 for engaging the formation at thewalls W of the well bore. The outer cutting edges 25 maybe atsubstantially uniform distances from the vertical axis of the tool. Theblades 24 are provided with lower cutting edges 26 for acting on theformation at the bottom of the well bore to make an annular cut. Thelower cutting edges 26 may be substantially radial relative to thevertical center of the tool or may extend slightly forward and outwardfrom the bit head. I Y

In the preferred construction, certain of the cutting blades 24 arelonger than the remaining blades so that their lower cutting edges 26are lower or spaced below the cutting edges of the other blades. In theparticular case illustrated in the drawings, one pair of diametricallyopposite blades 26 project some distance downwardly from the lower endof the bit head 20 to have their lower cutting edges 26 some distancebelow the lower end of the bit head, while the other two diametricallyopposite blades have vtheir lower edges 26 at or adjacent the lower endof the bit head. It will be apparent that the cutting edges 26 of thetwo longest blades 24 act on the formation at the bottom of the wellbore before the cutting edges of the other blades; and, upon the longblades becoming worn, the shorter blades may act on the formation at thebottom of the 1,923,486 rel 10 is adapted to be carried or operated onthe bore. The cutting edges 26 of the several blades are` preferablyinclined downwardly and outwardly toward the walls W of the well bore toprovide for rapid cutting of the formation and so as to carry thecuttings toward the peripheral walls of the well bore. f

The bottom or active cutting edges 26 of the several blades 24 extendinwardly to the interior of the bit head 20 or to points below the innerwalls of the bit head 20. The two shorter blades 24 are provided withcutting teeth 27. A tooth 27 is provided on each of the shorter blades24 at the inner end of its cutting edge 26. The teeth or cutting parts27 project downwardly from the lower end of the bit head ,2D so thattheir lower cutting edges may be in substantially the same horizontalplane as the cutting edges 26 of the longer blades. The lower edges ofthe teeth 27 may be beveled or sharpened and may be substantially normalto the longitudinal axis of the well borepand tool. The upper edges 28of the blades 24 may be inclined downwardly and out-` wardly tofacilitate withdrawal of the drill from the well bore.

'Ihe inner barrel or core barrel l2 is provided to receive and retainthe core C and is arranged longitudinally within the outer barrel 10.The core barrel '12 is centrally disposed within the outer barrel 10 andis of smaller diameter than the outer barrel l0 to provide an annularfluid passage F between the'two barrels. In accordance with the standardpractice, the core barrel 12 may be comparatively long and may beprovided at its upper end with a means for discharging fluid whenreceiving the core C. A suitable relief or discharge valve may beprovided on the upper end of the core barrel 12 to permit displacementof fluid from the core barrel upon the core being passed into its lowerend. In the particular embodiment of the invention disclosed in thedrawings, a tubular cap 29 is screw-threaded on the upper end of thecore barrel and a ball 30 is provided to control the passage of fluidthrough the cap. A crown 31 is mounted on the cap 29 around the ball 30to prevent displacement of the ball.

It is a feature of the present invention that the core barrel 12 and theparts associated therewith are longitudinally or"vertica1ly movablerelative to the outer barrel 10. Means is provided for 125 slidablyguiding and centering the upper end portion of the core barrel l2. Aplurality of spaced guides or splines 32 are provided on the inner wallsof the outer barrel 10 to slidably engage the cap V29. The splines32operate to slidably 130 guide and center the core barrel within theouter barrel 10 and are spaced apart so as to permit the free downwardpassage of the fluid through the annular spaceF.

The inner cutter or core cutting means 13 is 135 provided to make anannular cut in the formation at the bottom of the well bore within theannular cut made by the blades 24. The inner cutting means 13 is carriedon or connected with the lower end of the core barrel 12 and, inaccordance with the invention, is removably connected with the corebarrel. In the embodiment of the invention being described, the innercutting means 13 includes an' elongated tubular r member or body 33attached to the lower end 14" of the core barrel 12 and carrying thecore attaching means 14. The lower end of the core barrel 12 isscrew-threaded into a socket 34 in the upper end of the cutter body-33.The body 33 is preferably of substantially the same internal andexternal diameter as the core barrel 12 so as to provide an annularspace or continuation of the uid passage F downwardly through the outerbody 19 and bit head 20. In accordance with the invention, the cutterbody 33 projects downwardly beyond the lower end of the bit head 20 andis provided at its lower end with the cutting means 13, as will behereinafter described.

The body 33 may have a loose or sliding connection with the outer bithead 20. A plurality of spaced outwardly projecting lugs are provided onthe body 33 to slidably fit longitudinal slots 36 in the interior orinner Wall of the bit head 20. In accordance with the broader aspects ofthe invention, the various features of the invention may be embodied ina tool in which the body 33 has a rigid connection with the bit head 20,for example, a connection in which lugs on the body 33 are immovablyheld in sockets or slots in the bit head 20. In the specic embodiment ofthe invention disclosed in the drawings, the lugs or projections 35 areslidable longitudinally or vertically in the slots 36 so that theassembly of the core barrel 12 and the cutter body 33 has limitedlongitudinally movement relative to the outer barrel l0 and partsconnected therewith. The end of the connecting pin 23 constitutes theupper ends of the slots 36, and the upper ends of the lugs 35 areadapted to engage the lower end of the pin 23 to limit upward movementof the body 33 and core barrel. The lower ends of the lugs 35 areadapted to engage the lower walls` or bottoms of the slots 36 to limitthe downward movement of the core barrel and body 33 with respect to theouter barrel 10 and bit head 20. The lugs or projections 35 aresutilciently heavy to effectively transmit the rotational strains fromthe bit head 20 to the cutter body 33 vduring operation or rotation ofthe tool and to support the core barrel and core during withdrawal oftl.e tool from the well bore.l

Y The cutting par ts on the lower end of the cutter body 33 are in thenature of a plurality of cir' cumferentially spaced blades or teeth 37.The cutting teeth 37 project downwardly from the lower end of the body33 and are inclined downwardly and forwardly relative to the directionof rotation of the tool. The cutting parts or teeth 37 projectdownwardly below the cutting edges 26 of the lowest blades 24. The loweredges 38 of the teeth 37 may be beveled or sharpened to effectively cutthe formation and may be substantially normal relative to the Verticalaxis of the tool. In accordance with the invention, the cutting teeth 37project radially inward from the interior of the body 33 so as to cut ortrim the core C to a size to readily pass upwardly into the core barrell2. Further, certain of the cutting parts or teeth 37 project outwardlyfrom the exterior of the body 33 suiicient distances so that their outeredges are in vertical planes spaced outwardly of the vertical planesoccupied by the inner edges of the blades 24 and, accordingly, so as tohave greater active or cutting radii than the blades 24. In this manner,the cutting action of the blades 24 and the teeth 37 overlap to ensurethe complete cutting of the formation at the bottom of the tool so thatprojections cannot remain on the formation to project upwardly betweenthe body 33 and the bit head 20. The wider cutting teeth 37, i. e., thecutting teeth which project outwardly beyond the inner edges of theblades 24, are adapted to extend into slots or sockets 39 provided inthe lower end of the bit head 20 when the body 33 and core barrel 12 arein the up position with respect to the bit head 20. The slots 39 areadjusted to pass these larger teeth 37 when assembling the tool. Thecutter body 33 extends into the annular cut made by the teeth 37 so thatthe iluid discharge downwardly through the annular passage F cannot Washout the bottom of the cylindrical core C' cut by the teeth 37.

The core catching or core retaining means 14 is carried by the body 33and includes a row or series of leaf springs 40 for engaging the core4C, and a plurality of pivoted dogs 41 for cutting and supporting thecore. y'The springs 40 may be attached to or carried by a ring 43arranged in the lower en d of the socket 34 and retained in position bythe lower end of the core barrel 12. The lower ends of the springs 40may be riveted or otherwise attached to the rings 43, and the springsextend upwardly and inwardly from the ring, asl illustrated throughoutthe drawings. During passage of the core C into the barrel, the springs40 are ilexed backwardly or outwardly and, upon the tool being movedupwardly to withdraw the core C, their upper edges bite into the core,as illustrated in Fig. 7 of the drawings.

'll'he pivoted dogs 41 are pivotally mounted on the interior oi the body33 and are operable to cut 0E the core C and to support or aid insupporting the core. The lower or outer ends of the dogs 41 arepivotally mounted in the lower ends of vertical recesses or slots 42formed in the inner walls of the body 33. Pivot pins 44 extend throughthe lower ends of the slots 42 and openings in the dogs to pivotallyattach the dogs to lthe body 33. In the preferred construction, the

'ends of the dogs 41 co-operate with the recesses lli 46 so that thethrusts or strains to which the dogs 41 may be subjected are directlytransmitted to the body 33 and do not subject the pivot pins 44 toexcessive strains. core C into the core barrel 12, the lugs 41 are in uppositions where their major portions are disposed within the slots 42.Spring means is provided for urging the dogs 41 downwardly and inwardlyto bite into the core. Aleaf spring 47 is mounted on the inner wall ofeach recess or slot 42 to normally urge the dog 41 into engagement withthe core C.

It is believed that the operation ol' the tool illustrated in Figs. 1 to7 inclusive of the drawings will be readily apparent from the foregoingdetailed description. As the tool is rotated and ied downwardly into theformation, the lower cutting teeth 37 operate to make an annular cut inthe formation to provide the cylindrical upwardly projecting core C. Thelowermost cutting edges 26 of the outer blades engage the formation atthe bottom of the bore to make an annular cut During passage of thearound the cut made by the teeth 37. It is to be noted that certain ofthe blades v37 make a cut in the formation having a larger outsidediameter than the inside diameter made by the cutting blades 24. In thismanner, the teeth 37 and the blades 24 overlap in their operation oraction on the formation to positively ensure the complete cutting awayof the formation at the lower end of the bit head 20. The outer edges 25of the blades cut and engage the walls of the well bore so that the tooldoes not have any eccentric or undesirable motion, thus ensuring smoothoperation of the drill. The circulation fluid is passed downwardlybetween the inner and outer core cutters through the passage F todischarge downwardly around the projecting end of the body 33. The fiuiddischarged at the lower end of the tool is eective in washing thecutting blades 24 and the cutting teeth '37. The downwardly projectingbody 33 prevents the discharged circulation uid from striking againstand washing out the core C being cut by the teeth 37. During normaloperation, the body 33 is in an up position where the lugs 35 are inengagement with the lower end of the pin 23 so that the teeth 37 areApositively fed into the formation. In the event that the drill passesthrough or breaks through a hard formation into soft formation, the body33 and parts connected therewith are free to drop or advance downwardlyahead of the cutting means 11 so that the core will not be destroyed orlost.

When it is desired to remove the tool from the well, the string of pipeP may be drawn upwardly so that the bottom ends of the slots 42 comeinto engagement with the lower ends ofthe lugs 35. The cutter body 33and core barrel 12 are then moved upwardly together with the outerbarrel 10. Upon upward movement of the tool, the spring fingers cut orbite into the core C and the dogs 41 bite into the core C. If desired,the

tool may be rotated after or when an upward strain is exerted on thestring P so that the dogs i1 may cut off the core C. After the core Chas been broken or cut from the formation at the bottom of the core, thedogs 41 are operable to assume substantially horizontal positions wherethey engage under the core and support the core within the barrel 12. Itis particularly noted that the invention provides a core drill in whicha free annular fluid'passage is provided between the inner andouterbarrels to pass fluid downwardly between the inner and outer cutters.The inner assembly is connected with the outer assembly in an effectivemanner without the use of screw-threaded connections and without the useof annular shoulders or abutting parts which might materially interferewith the downward circulation of fluid between the two barrels. The

' lug and slot connection between the body 33 and the outer bit head 20permits the provision of the annular fluid passage F and provides forthe effective transmission of the operating strains from the body 33 tothe outer assembly. o

In the embodiment of the invention illustrated in Fig. 8 of thedrawings, the outer barrel 10 and 4the outer cutting means 11 may beidentical with those described above, and the, core barrel may besimilar to the core barrel 12 described above. In this form of theinvention, the core catching means 14B includes two annular rows or setsdf spring fingers 60. The upper set of spring fingers 60 may be mountedin the same manner as the fingers 40 described above, i. e., 'they-maybe carried by a\ ring 61 arranged in the interior of the tool and heldbetween the lower end of thev core barrel 12 and a shoulder 62. In theconwalls of the sub 63 so that a ring 61 is carried by j the member orsub 63. The sub 63 has a pin 64 on its lower end screw-threaded into asocket 65 V in the upper end of the cutter body 33a. The lower set ofspring fingers 60 for gripping and retaining the core are carried by anannular member or ring 66 arranged in the bottom of the socket 65. Thering 66 isiheld in position by the lower end of the pin 64 threaded intothe socket. The several fingers 60 project upwardly from the rings `61and 66 and their upper ends may be bowed inwardly to effectively engageand carry the core. The other parts of the drill illustrated in Fig. 8of the drawings may be similar to the corresponding parts illustrated inFigs. 1 to'7 inclusive of the drawings and described above.

The tool illustrated in Fig. 8 of the drawings operates in substantiallye same manner as the embodiment of the invention first described. The

two sets of core catching spring fingers 60 are.

operable to effectively gripand support the core.

Having described only typical preferred forms of my invention, I do notwish to^limit myself to the specific details set forth, but wish toreserve to myself any changes or variations that may appear to thoseskilled in the art or fall within the scope of the following claims:

Having described my invention, I claim:

1. A well tool of the character described including, an outer barrel, abit head detachably mount-v ed on the lower end of the barrel havingcutting parts for making an annular cut in the formation, a core barrelin the outer barrel movable longitudinally relative to the outer barrel,an annular body. on the core barrel projecting downwardly below thelower end of the bit head, cutting blades on the body projectingdownwardly below the said cutting parts and projecting outwardly betweenthe said cutting parts, there being an annular fluid passage between thecore barrel and body and the outer barrel discharging around theprojecting end of the body, and a lug on the body cooperating with avertically elongate .socket in the bit head to limit longitudinalmovement of the core barrel and body in both directions.

2. A well tool of the character describedincluding, an outer barrel,cutting means on the lower end of the outer barrel to make an annularcut in the formation, a core barrel within the outer barrel, a tubularbody on the lower end of the core barrel having cutting parts below thesaid cutting means, there being an annular fluid passage between thecutting means and the said body, and a connection between the outerbarrel and core barrel whereby the core barrel is movable longitudinallyrelative to the outer barrel and is rotated with the outer barrelincluding an integral lug on the said body extending into an elongatesocket in the said cutting means and adapted to engage the lower endwall of the socket to limit downward movement of the core barrel andbody.

3. A well tool of thecharacter described includ-r ing, an outer barrel,cutting means on the lower end of the outer barrel to make an annularcut in the formation, a core'barrel within the outer lthe said cuttingmeans, there being an annular fluid passage between the cutting meansand the said body, and a connection between the outer barrel and corewhereby the core barrel has limited longitudinal movement relative tothe outer barrel and is rotated (with the outer barrel, said connectionincluding lugs von the body co-operating with sockets in the saidcutting means and adapted to engage the lower ends of the sockets tolimit movement of the core barrel and body.

roamed 4. A well tool oi' the character described including, ari/outerbarrel, a bit head on the lower end lof the outer barrel having spacedcutting blades to make an annular cut in the formation, a core barrelwithin the outer barrel, a tubular body on the lower end of the corebarrel having cutting parts projecting below the said cutting blades andprojecting outwardly between said blades, there being an annular fluidpassage between the cutting means and the said body, core catching meansin the core barrel, and a connection between the outer barrelvand corebarrel whereby the core barrel has limited relative longitudinalmovement relative to the outer barrel and is rotated with the outerbarrel and is spaced from the 'outer barrel to provide said annularfluid passage, said connection including circumferentially spaced lugson said body slidably cooperating with elongate sockets in the interiorof the bit head. j

5. A well tool of the character describedfincluding, an outer barrel,cutting means on the lower end of the outer barrel, a core barrel withinthe outer barrel, a tubular body on the lower end of the core barrelhaving cutting parts, a connection between the outer barrel andthe corebarrel whereby the core barrel is rotated with the outer barrel and ismovable longitudinally relative to the outer barrel, said connectionincluding a lug portion on the said body slidably cooperating with agroove in the outer barrel,v and a dog pivotally mounted in a socket inthe said lug portion operable to cut a core upon rotation of the tool.

6. A well tool including an outer barrel, a bit head on the lower end ofthe outerbarrel operable to make an annular cut in the formation, aninner barrel within the outer barrel, a tubular body on ymounted in therecesses.

the outer barrel to provide an annular uid passage around the innerbarrel and said body, there being sockets in theinterior of said body inthe lug portions, and core engaging dogs pivotally mounted in the lastmentioned sockets.A

L well tool includingan outer barrel, a bit head on the lower end of theouter barrel operable to make an annular cut in the formation, an innerbarrel within the outer barrel, a tubular body on the lower end of theinner barrel having cutting partsprojecting below the bit head, lugportions on the said body cooperating with vertically elongate socketsin the bit head to connect the inner barrel with the outer barrel forlimited longitudinal movement relative .to the outer barrel ,and spacingthe inner barrel and the said body from the outer barrel to provide anannular fluid passage around the inner barrel and said body, there beingsockets in the interior of said ybody in the lug portions, core engagingdogs, and pins pivotally mounting the dogs in the last mentionedl'barrel withinthe outer. barrel, a tubular bodydetachably connected withthe lower end of the inner barrel and having cutting parts projectingbelow the bit head, lugportions on said body cooperating with verticallyelongate sockets in the bit head to connect theinner barrel and the bodywith the outer barrel for limited longitudinal movement relative to theouter barrel and spacing the inner barrel and said body from the outerbarrel to provide an annular fluidpassage around the inner barrel andsaid body, and operable to prevent loss of the said' body in the eventthat it becomes disconnected from the inner barrel, there being recessesin the interior of the said body in the lug portions, and core engagingrdogs pivotally

